1. Field of the Invention
The present invention relates to a bellows apparatus. More specifically, the present invention relates to a bellows apparatus capable of effectively restricting elongation and contraction of the bellows main body.
2. Description of the Prior Art
As a bellows apparatus having the construction to restrict elongation and contraction of the bellows main body, there have heretofore been known the apparatuses of the type as illustrated in FIGS. 1 through 3.
Namely, plural first, second and third guide metals 53, 63, 73 are integrally provided to the bellows main body 51 with a predetermined spacing therebetween in the axial direction. These first, second and third guide metals 53, 63, 73 have a flat annular shape and their outer circumferential section is integrally secured to the bellows main body 51. Cylindrical first, second and third guide members 55, 65, 75 are integrally shaped at the inner circumferential edge section in the direction of diameter of the first, second and third guide metals 53, 63, 73 and extend in one of axial directions (upwardly in the drawing). Cylindrical first, second and third guide members 56, 66, 76 are integrally shaped with the guide metals 53, 63, 73 and extend in the other of axial directions (downwardly in the drawing). These first, second and third guide members 56, 66, 76 have a diameter which is greater than the diameter of the abovementioned first, second and third guide members 55, 65, 75. On the other hand, first and second locking plates 57, 67 are shaped at the edge section in the axial direction of the first and second guide members 55, 65 and extend outwardly in the direction of diameter. Furthermore, second and third locking protuberances 68, 78 are shaped at the edge section in the axial direction of the second and third guide members 66, 76 and extend inwardly in the direction of diameter.
The bellows apparatus of the prior art having the abovementioned construction has drawbacks to be described.
(1) When the gap is L between the second guide metal 63 and the third guide metal 73 at maximum elongation of the bellows main body 51 as shown in FIG. 1, the gap is approximately L/2 between the second and third guide metals 63 and 73 at maximum contraction of the bellows main body as shown in FIG. 2. In other words, the upper limit of the rate of elongation of the conventional bellows apparatus has been two times. For this reason, it has been impossible to effectively utilize the elongation and contraction of the bellows main body 51.
(2) In addition, the first, second and third guide members 55, 65, 75 are arranged such that they are superposed upon the first, second and third guide members 56, 66, 76, respectively, in the direction of diameter. Hence, the thickness X in the direction of diameter of the bellows apparatus becomes W+C.sub.1 +T.sub.1 +C.sub.2 +T.sub.2 where W is the thickness in the direction of diameter of the bellows main body 51; C.sub.1 is the gap between the inner circumferential surface of the bellows main body 51 and the outer circumferential surface of the first, second and third guide members 56, 66, 76; T.sub.1 is the thickness in the direction of diameter of the first, second and third guide members 56, 66, 76; C.sub.2 is the gap between the inner circumferential surface of the first, second and third guide members 56, 66, 76 and the outer circumferential surface of the first, second and third guide members 55, 65, 75; and T.sub.2 is the thickness in the direction of diameter of the first, second and third guide members 55, 65, 75. Since the thickness X becomes thicker, the bellows main body 51 has only a limited space therein that can be effectively utilized.